James Hansen Talks About Climate Change

Editor’s Note: If any single event can be said to have put climate change on the world’s policy radar, it was the testimony of NASA scientist James Hansen before Senator Tim Wirth’s committee in Congress on June 23, 1988. On the eve of the twentieth anniversary of that event, World Watch’s Ben Block talked with Hansen about its impact.

World Watch: What led you to your 1988 testimony?

James Hansen: This was the culmination of years of work, going back at least to three papers between 1981 and 1982, [discussing] carbon dioxide and climate change in the journal Science, other trace gases in Geophysical Research Letters, and sea level, also published in Science. What was different in 1988 was that I had a more comprehensive paper completed and in press at Journal of Geographical Research, which was the attachment to my 1988 testimony.

WW: What did you expect the impact of your testimony would be?

JH: Well, the intention was to get some public exposure. Rafe Pomerance [founder of the Climate Policy Center, who was then aWorld Resources Institute senior fellow] visited me after reading our 1981 Science paper [on carbon dioxide] and encouraged me to testify to Congress, which I did a few times in the 1980s without much effect. The hope was to get more attention this time, which seemed possible given the extreme U.S. climate [hot weather] in 1988.

WW: Looking back, how did it go?

JH: It certainly got the desired attention. My regret, shortly thereafter, was that I had not discussed the impact of global warming on the hydrologic cycle in a more general way. Global warming means more moisture in the atmosphere, so heavy rain events and floods will increase. But, at times and places when it is dry, drought intensity will increase. Because of the emphasis on drought in 1988, I decided to testify again in 1989. That testimony got a lot of attention also, because I complained about [the White House’s Office of Management and Budget] changing my testimony, but that hullabaloo caused the message about the hydrologic cycle to be lost.

WW: When many scientists responded to the ’88 testimonies that you were “ahead of the science,” how did you react?

JH: I was not too concerned about that; I knew that within not many years it would become obvious whether or not I was right. Since I was very confident that I was, I thought there was some value of, in effect, making a prediction.

WW: Since you told the press that your climate-change observations were being censored by the Bush administration around 2005, how did it change your role in shaping the public discourse on climate change?

JH: It probably has given more attention to the matter. The New York Times press coverage did not do a good job of tracking the censorship to its source, instead attributing it to a 24-yearold renegade. Mark Bowen’s book, Censoring Science, tracks the problem to the top.

WW: Over the past 20 years, what developments in science, policy, or public perceptions—or lack thereof—have surprised you the most?

JH: I have to admit that I am surprised and disappointed at the lack of substantial action to mitigate climate change. I am impressed by many of the people, senators et cetera, that I met in Washington, yet Washington seems to be under the heavy thumb of special interests, especially fossil fuel special interests. Clearly they have not succeeded in doing what is best for the people; rather they are doing what is best for big business.

WW: How often do you think the government is attempting to distort results of scientific research?

JH: Almost all scientists in the Environmental Protection Agency say that they cannot say what they believe if it goes against the [Bush] administration’s preference. In NASA it was the same (if policy-relevance was involved) until the administrator gave a green light. My impression is that things have improved, but they are still not good. My information is based on hearsay from a small number of scientists, but also on broader studies such as the last one conducted by the Union of Concerned Scientists. This attitude of the administration is idiotic, not just because it violates basic principles of democracy, but because it leads to lousy policymaking. Why do you need advice of scientists, if you know that you are only going to accept results that fit predetermined policy decisions?

WW: Numerous governments and NGOs around the world are calling to limit the atmosphere’s temperature increase to 2 degrees C. Do you believe this to be a safe limit, and do you think this target is achievable?

JH: That target is easily achievable with sensible policies. Unfortunately, warming that large is a guarantee of global disasters. We are already within a fraction of one degree of the warmest interglacial periods. Two degrees C would put us into the range of the Middle Pliocene [the last period of geological time, 3.5 to 2.5 million years ago, of greater global warmth]. Unfortunately, based on polar temperature maxima, we overestimated the warmth of prior interglacial periods.

WW: Some scientists have argued that we have already reached tipping points in some regions of the world. Do you agree? If so, what are they and can we avoid them?

JH: We need to distinguish tipping level and the point of no return, as explained in our new “Target CO2” paper. The tipping level is the level of greenhouse gases that will lead to large, undesirable, even disastrous, effects. We have reached the tipping level for several important effects. That is why we must go back in CO2 amounts at least to 350 ppm and possibly lower. The point of no return is when the dynamics of the process take over and it is out of our control, we cannot stop it, e.g., the ice sheet from disintegrating, because of positive feedback and warming in the pipeline. Some phenomena have enough inertia that we can afford some overshoot of the safe CO2 level, provided that we get back to a lower amount fast enough. The ice sheets and sea level may be in that category. Unfortunately, Arctic sea ice has reached the point where we are going to lose all of the warm season ice within the next few decades.

WW: Often the more you know about the hard realities of climate change, the more depressing it becomes. What inspires you to be hopeful?

JH: It becomes readily solvable if we do just a few things that make enormous sense for other reasons. By far the most important is a moratorium on new coal-fired power plants (unless they capture CO2) and a phase-out over the next two decades of existing ones. We will also need a high enough price on carbon emissions to avert substantial use of unconventional fossil fuels (tar shale, tar sands). Moving beyond fossil fuels sooner (we would have to do it within several decades anyhow) makes enormous sense for many reasons (cleaner air and water, energy independence, et cetera) for everybody except a handful of fossil fuel executives, but, unfortunately, they wield enormous power in our governments, and not just in the United States. I still believe that our democracy can work, but it requires overcoming the undue influence of money in politics.

WW: You have repeatedly called for a moratorium on coal power plants and have even written to leaders of U.S. states and countries that are considering new coal plants. What reactions have you received to these letters?

JH: Perhaps it helped in the United Kingdom, but it remains to be seen. At least the opposition leader has come out with a position in favor of a moratorium. But [a conventional coal-fired power plant in] Kingsnorth [Kent, UK] is still up in the air. Germany [is] unclear. I have been invited to come over and talk with the minister of the environment. The governor of Nevada is in the hip pocket of the coal industry. I am afraid that the same is true in Minnesota (despite the greenwashing of him) and Virginia. Perhaps utility CEOs are more important. [International investor] Jim Rogers has been greenwashing, but maybe he is open minded. I am having dinner with him soon. I had a very good meeting with the CEO of [energy service company] Public Service Enterprise Group.

WW: After a long career of achievements, what would you like to accomplish before you leave NASA?

JH: There are several papers that I am working on that I believe to be significant. And, somehow, I need to be able to write more clearly, so that the implications are understood and believed.